Ubuntu: Why does my ubuntu 18.04 get stuck on the 'purple' screen after logging in?

Question:

Please provide me with a detailed answer explaining why my Ubuntu 18.04 gets stuck on the purple screen after trying to log in. Is it some bug in Ubuntu or do i need to install some additional drivers or something? I have an AMD RADEON GRAPHICS Chip in my laptop (in addition to intel i5) which isn't configured yet and which might be causing this issue. Are there any commands I can use on that purple screen to get around it because right now i can only avoid it by performing a force shut down of the system using the power button.

Solution:1

There are two relevant bug reports on the "purple screen" in Ubuntu 18.04 LTS. Many people have encountered difficulties including myself. However my problem seems different than the two bug reports so there might be more in the future regarding this issue.